Plasterboard preparation

Hi.

I am doing a loft conversion / renovation of a few other rooms and have been putting up plasterboard and had a few questions.

1. I really don't want any cracking on PB joints that I have seen at many other properties. I assumed this is dude to lack of screws on board edges allowing too much flex on seams. I have therefore doubled up on screws on the edges and they seem far more solid but to do this on the pitched roof I have had to add vertical battens between all the horizontal battens (the horizontal battens were fixed as requested by building inspector at 400mm centres running the length of the roof which sit on top of TLX (the silver foil insulation).Is my adding of vertical battens overkill as in my mind these are needed to give a pick up for the side edges of the plasterboard. I have never seen this done on the few other builds I have witnessed and they just butt up the boards and rely on the screws on the horizontal battens to do the job. Is this just cutting corners or normal? Also with so many screws should I be concerned about plaster popping on the screw heads and consider scrim tape on these? Again I have seen many popped screw heads in my house on drywall but assumed this is more due to lack of screws allowing flex rather than the plaster not adhering to the screw. Also I will be skimming and the walls I have seen this on were taped and jointed.

There is also one board (the first one I fitted) that I don't have this vertical pickup on and point in case it flexes more at the edges where butted up to the board along side it. I am trying to avoid the urge to remove it and fit a vertical batten and wondered is the skim or even some expanding foam or bonding in the 1mm gap between them might help strengthen them.

My last concern was there are quite a few screw holes in boards where I had removed them to add battens or missed a batten and don't know if these are fine and will simply disappear and. It be an issue after skimming or not. I guess this all boils down to the fact that being new to this I am not sure how much is needed in the prep stage versus what can be sorted at the skimming stage.

Cheers in advance for any advice.

AnswerHi,With spacings of 400mm it should be fine to butt the boards up, without the vertical battens (acting as noggins) but it definitely will not do any harm to have them. As long as the boards are securely fixed and there is no substantial flexing of the boards all will be fine. The best way to prevent any cracking is with the use of scrim tape. It is self adhesive and can be applied before you start plastering. If you are at all concerned then put 2 layers on - this will ensure nothing will crack. If you are particularly concerned about any individual areas then apply 2 layers of scrim tape, push a small amount of plaster in and apply another layer of scrim tape to bed into the plaster and smooth off as flat as possible prior to skimming. This really will prevent any cracking, and should be all that is needed on the area you are concerned about.

The screw heads will only pop if the board is not properly fixed. If the board has not been properly pushed back to the timber and there is a slight void, and in the future the board is pushed back due to movement or fixing something onto the wall, the board will move back - but the screw stays exactly where it is and the plaster is pushed off. To avoid this - as the board is being fixed - it should be pushed in to he fixing point very firmly.

The holes will be fine - however if you're concerned - just put some scrim tape over.

As long as the boards have been pushed in hard when fixing - to ensure they are properly fixed and you use lots of scrim tape - you should have no problems.